It is widely acknowledged that heat is produced during operations of electronic devices such as clipsets or processors of computers. The faster the operation speed is, the larger the amount of heat produced by the electronic device is. However, excessive heat accumulated at the electronic device is likely to affect operations of the electronic device and even results in computer crashes. Therefore, a heat dissipation device such as a heat sink is needed for heat dissipation of the electronic device.
In order to keep the heat sink into close contact with the electronic device, retaining devices such as retainers or fasteners are generally required. FIGS. 7–8 illustrate a prior art heat sink retainer 20 used for attaching a heat sink 40 to a central processing unit (CPU) 50 mounted on a socket 60. The socket 60 has a pair of catches 601 formed at opposite sides thereof, for engaging with the retainer 20. The retainer 20 includes a main body 210 and a bolt 220. The body 210 has a central pressing portion 211 for pressing the heat sink 40 onto the CPU 50. First and second latching arms 212, 213 respectively depend from two free ends of the central pressing portion 211. Each latching arm 212, 213 defines an opening 214, 215 for receiving a corresponding catch 601 of the socket 60. A V-shaped spring portion 216 extends outwardly from a central section of the second latching arm 213, for adjusting the height of the second latching arm 213. In assembly, the openings 214, 215 of the latching arms 212, 213 loosely receive the corresponding catches 601 of the socket 60, and then the blot 220 is screwed into a hole 217 defined at the spring portion 216 to adjust the height of the second latching arm 213. As a result, the openings 214, 215 of the latching arms 212, 213 securely receive the catches 601 of the socket 60 and the central pressing portion 211 exerts a downward force on the heat sink 40 to thereby maintain the heat sink 40 into close contact with the CPU 50. However, this kind of retainer needs a special tool during mounting or dismounting of the heat sink, which is not appreciated by users or operators.